A numerical study on fluid elastic vibrations of multiple cylinders in cross flow

Abstract

The flow‐induced vibrations of cylinder arrays subjected to cross flow are studied numerically. Multiple cylinders, two to seven identical cylinders, in a rotated triangular array are investigated, with an emphasis on neighborhood‐cylinder effects on the onset of fluid elastic vibrations for a monitored cylinder. The instantaneous velocity and pressure distributions of the fluid flow, and the fluid forces on cylinder surfaces are computed numerically. The displacements of the cylinders, due to the fluid forces, are then calculated as a function of time, to describe the cylinder motions in the flow. From the amplitude responses of the cylinders, it is illustrated that fluid elastic vibrations with significant amplitude occur in multiple cylinders as the freestream velocity goes beyond a critical value, while a single cylinder can only exhibit vortex‐induced vibrations with relatively small amplitude in a narrow velocity range. Beyond the critical velocity, the cylinders vibrate in elliptical orbits. Amplitude diagrams are used to determine the critical velocity for the onset of the fluid elastic vibrations. It is shown that with more upstream cylinders, the critical velocity of the monitored cylinder decreases, implying that the cylinder becomes more fluid elastically unstable. However, the critical velocity of the cylinder does not change as more adjacent cylinders are added downstream.

Key words:

• flow‐induced vibrations
• computational fluid dynamics
• cylinder arrays

Notes

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